The present invention is an improvement is a locking device for preventing an unintended movement of the slide gate door of a railway hopper car from the closed to the open position. Various devices for accomplishing this purpose are known to the art, as for example, U.S. Pat. Nos. 2,142,236, 2,749,851 and 3,707,126.
One advantage of the present invention as compared to the known devices is that the locking device has some resiliency in resisting a force tending to move the slide gate door in the opening direction. Railway cars are subjected to numerous impact forces, some of which are quite severe. For example, when a railway car moves down the hump in a classification yard it likely will impact upon other cars on the track ahead of it and the impact can be exceedingly forceful. While shock absorbers are built into the coupling units of cars, still there are severe shock loads within the body of the car and its content. Such shock loads can affect the position of the slide gaste door due to its inertia, with the slide gate door thus impacting against its locking device (depending upon the sense of the shock force). The present invention makes available a construction in which there need be no play, or lost motion, when the slide gate door is locked closed, and which includes a spring element to absorb shock forces applied in the sense of the door opening direction.
Another advantage of the invention is the simplicity available to obtain a good fit during the course of manufacture. As compared to the available state of the manufacturing art, the manufacturing techniques employed in producing railroad hopper cars and their components are not very sophisticated, perhaps even crude. That is, in the main the components are not made with very close tolerances because such criticality is quite unnecessary and the expense of achieving close tolerances is unjustified. The application is such that the monetary savings achieved by using forming and fabricating techniques which do not result in close tolerances is important. Through the use of the present invention it is quite simple for the workers who are putting the car together to make adjustments necessary to achieve a good fit even though the tolerances up to that point have been sufficiently loose such that it would be only by accident that a good fit was achieved.
Further objects and advantages will become apparent from the disclosure herein of an embodiment of the invention.
In the present invention a plate is imposed between the leading (in the opening sense) edge of the slide gate door and a cam pivotally mounted on the car frame, which plate is positioned and arranged to serve as a spring. The plate is welded to that edge of the door and the plate's distal side is located slightly above the door supports. That part of the cam face that engages the distal side of the plate is arranged to cam the plate toward those supports, whereby the plate is blocked against significant movement in the door opening direction, and serves as a spring resisting forces applied in the sense of the door opening direction.